Where the Midwest Ends and Great Plains Begins in South Dakota

For generations, South Dakotans have used the Missouri River as a sort of boundary between the Midwest and the Great Plains. Every resident seems to know this, and anyone who's traveled from East River to West River can see the stark differences, once you cross the "Mighty Missouri".

But a silent and invisible shift is moving that border away from the river and closer to towns like Mitchell, Huron, and Aberdeen. And it's taking the typical, humid, lush Midwest that many East River residents grew up with, right along with it.

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Has the 100th Meridian Moved to the 98th Meridian?

The 100th Meridian West Line runs through the states of North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, and Texas. What does it mean? Basically, everything east of the line (Iowa, Minnesota, Missouri) has more green in its environment, while everything west (Western South Dakota, Wyoming, Montana) has a more arid environment.

While the 100th Meridian (near Pierre) used to be where the Midwest ended and the Great Plains began, Climatologists and Scientists have begun to shift that line to the 98th Meridian. This is near the towns of Mitchell, Aberdeen, and Huron. Why the change? To put it simply: less annual rainfall.

Let's take a look at Mitchell, specifically. Here are some of the total precipitation amounts for the town over the years:

• 1915: 29.1 total inches
• 1960: 25.6 total inches
• 1985: 28.4 total inches
• 2010: 27.8 total inches
• 2020: 16.1 total inches
• 2021: 17.4 total inches
• 2022: 12.3 total inches
• 2023: 20.6 total inches
• 2024: 23.8 total inches
• 2025: 19.0 total inches

With rainfall totals being slightly less, the invisible line that shapes the state of South Dakota's agricultural landscape has shifted eastward. But this shift has also led to new opportunities. More and more farmers are turning to wheat (opposed to corn and soybeans) as a reliable crop to plant year in and year out. In other parts of the US that fall along the line, many farmers are choosing crops like wheat, sorghum, and sunflowers, and this has proven to be a profitable venture.

What does the future hold for Eastern South Dakota? Will corn and soybeans continue to be the dominant crops from now on, or will wheat begin to take their place in local farm fields? That's to be determined, but one thing's for sure: South Dakota farmers will have plenty of options for crops as we advance.

Check out this YouTube video for more information on this invisible line and how it shapes the state of South Dakota (and the entire Great Plains) below.

Story Sources: Geography Realm Website, Yale Environment 360 Website,